Field of the Invention
This disclosure relates generally to elevator arrangements and, more particularly, to an elevator arrangement configured to move at least two elevator cars independently in at least one hoistway.
Description of Related Art
Elevator arrangements and methods of moving elevator arrangements in hoistways are well known in the art. Many of the existing elevator arrangements include one elevator car assigned to one hoistway. In current elevator arrangements, the number of elevator cars needed to satisfy the traffic demand in a building is equal to the number of hoistways provided in the elevator arrangement. The building floor area occupied by the hoistways is typically not available for renting or selling. In an effort to obtain more useful building area (or in existing buildings, more traffic capacity), elevator arrangements with more than one elevator car in at least one hoistway were introduced. These elevator arrangements included linear motor propulsion systems or multiple machine rooms on top of the hoistways to move the elevator cars in the arrangement.
European Patent No, EP 1 693 331, the disclosure of which is herein incorporated by reference in its entirety, discloses an example of one such elevator arrangement. In this elevator arrangement, each car is assigned to one hoistway propulsion system in the assigned hoistway. Any changes of the assigned elevator car and/or hoistway propulsion system are not possible as long as the elevator car stays in the assigned hoistway. The necessary number of hoistway propulsion systems is equal to the maximum number of elevator cars in each hoistway.
A further elevator arrangement is shown in Japanese Patent Nos. JP 3177293 and JP 930756, the disclosures of which are herein incorporated by reference in their entirety. These elevator arrangements use multiple overlapping propulsion systems in one hoistway to assure a continuous car movement during the exchange of the cars within the hoistway propulsion system. The multiple overlapping propulsion systems require more available space in each hoistway and can often interrupt the movement of the elevator cars, thereby causing turbulence when moving through the hoistways.
Another elevator arrangement is disclosed in International Patent Application Publication No, WO 2009/036232, the disclosure of which is herein incorporated by reference in its entirety. In this elevator arrangement, the hoistway propulsion system is mounted on the front and rear walls of the hoistway. Each elevator car is driven and propelled by a single drive assembly that includes a pulley system for driving the elevator car. This elevator arrangement requires at least four parallel and simultaneous working propulsion systems to move one elevator car in one hoistway in order to reach a balanced load transfer between the propulsion/guiding system and the elevator car.